This review is devoted some aspects of the phenomenon of field electron emission per se, its governing relationships, attainable parameters of the field emission process and its application to problems of vacuum micro-electronics. The field electron emission is also a process capable of initiating and sustaining the generation of high-power and super-high-power electron beams through a phenomenon called the explosion electron emission, which is the basis of the modern high-current electronics. The contents of the review are given below. (C) 2003 Published by Elsevier Science B.V.